In recent years, insulating glasses have attracted attention from the viewpoint of energy saving, and they are commercial products, the demand of which continues to increase. For their production, many steps are required. Accordingly, their costs are high as compared with usual glass sheets, and it is desired to further lower the costs.
Most of insulating glasses presently available have a structure as shown in FIG. 4, wherein at least two glass sheets 1a and 1b are arranged to face one another via a spacer 2 to form an air space layer between the glass sheets 1a and 1b. And, a primary sealing material 3 is interposed between the spacer 2 and the glass sheets 1a and 1b to insulate the air space layer from the external air, and a cavity (recess) defined by the peripheral surface of the spacer and the inside surfaces of the peripheral portions of the glass sheets facing to one another, is sealed by a cold-setting secondary sealing material represented by a polysulfide type or a silicone type sealing material.
Heretofore, various improvements in productivity by simplification or automation and attempts for cost down have been studied and proposed for the process for producing insulating glasses. For example, a system for folding an aluminum spacer, or automation of the method of injection the cold-setting sealing material, may be mentioned. Further, as shown in FIG. 5, a method of employing a resin having a drying agent kneaded therein, as a spacer 4 instead of an aluminum spacer, has been proposed.
However, an insulating glass employing such a cold-setting sealing material requires curing for a long period of time for setting of the sealing material after preparation of the insulating glass, irrespective of the type of the spacer used. Accordingly, the product can not be shipped until completion of the curing.
Thus, it is necessary to provide a space for curing in the plant and to ship the product after storing it for a predetermined period of time, whereby the time period of delivery tends to be long, and it has been difficult to meet the demand of customers. Further, in order to comply with the demand which appears to increase in future, a wider space for curing will be required, and to secure adequate supply of insulating glasses while avoiding such a wider space, it is considered necessary to shorten the curing time.
From the viewpoint of lowering the costs for insulating glasses, a method has been proposed in which a molded product made of a resin having a drying agent kneaded therein is used as a spacer, and an insulating glass is prepared without using a secondary sealing material (JP-B-61-20501). However, this resin for spacer is inadequate in hardness as a spacer, and with the spacer made of the above resin alone, it has been practically difficult to maintain the shape of an insulating glass.
Further, an insulating glass is known in which a material having a drying agent kneaded into an extrusion moldable hard resin, for example, a thermoplastic resin such as a vinyl chloride resin or a hot-melt butyl and having a JIS A hardness (EsA) of 95, is used as a spacer (JP-A-7-17748). However, if this material having a hardness of HsA95 is used as a spacer or a sealing material for an insulating glass, the stress which will be exerted to the glass sheets or the sealing portion of the insulating glass will be so large that there will be difficulties such that the sealing portion undergoes peeling or the glass sheets of the insulating glass undergo breakage. Accordingly, at present, no insulating glass is known which fully satisfies the properties such as useful life, dimensional stability and moldability required for an insulating glass solely by a spacer without using a secondary sealing material.
Meanwhile, as illustrated by a hot-melt butyl in the above-mentioned publications, a butyl type rubber is used as a sealing agent for building material by virtue of its adhesive property, high weather resistance and low moisture permeability. However, the hardness is low, and it has a cold flow property. Accordingly, depending upon the particular purpose of use, it has a problem from the viewpoint of durability for a long period of time, if used alone. Further, it also has a problem that the melt viscosity is high, and the operation efficiency is poor. To improve the hardness, it has been proposed to mix various fillers, but if it is attempted to improve the hardness only by adding a filler, the melt viscosity tends to increase, whereby the operation efficiency will be impaired, and in some cases, the tensile strength or the tear strength tends to be low, such being undesirable.
Namely, the butyl type rubber has a function to seal the interface between the spacer and the glass sheets and to maintain the air tightness, and thus it is suitable for use as an end sealing material for an insulating glass. In such a case, as the hardness of the butyl type rubber is low, it is common to use a spacer made of a metal such as aluminum, and the butyl type rubber is disposed as a sealing material between the spacer and the glass sheets. Thus, the process for producing an insulating glass will be complicated, since it is required to use a spacer made of a metal as described above.
Accordingly, it is desired to develop a sealing agent which does not require a spacer made of a metal and which is capable of simplifying the production process. At present, no insulating glass has been known which fully satisfies the properties such as useful life, dimensional stability and moldability required for an insulating glass solely by a spacer without using a secondary seal.
An object of the present invention is to provide a resin composition which satisfies properties required for use as building material, particularly a resin composition for a spacer which does not substantially require the above-mentioned secondary sealing material in an insulating glass. Further, another object of the present invention is to solve the problem of curing which requires a long period of time after the preparation and to provide an insulating glass which is capable of realizing high productivity which has not been attained heretofore.